Apparatus for statically balancing machines for driving rotary components



Sept. 23, 1969 v. GOSCHE 3,468,189

APPARATUS FOR STATICALLY BALANCING MACHINES FOR DRIVING ROTARY COMPONENTS Filed Oct. 26, 1967 2 Sheets-Sheet l Sept. 23, 1969 v. GoscHE 3,468,189

R T TICA BALANCIN ACHINES APPARATUS F0 R NG R0 Y COMPONE 8 Filed 001;. 26, 1967 2 Sheets-Sheet 2 United States Patent 3,468,189 APPARATUS FOR STATICALLY BALANC- ING MACHINES FOR DRIVING ROTARY COMPONENTS Volker Gosche, Kornelimunster, near Aachen, Germany,

assignor to Schumag Schumacher Metallwerke Gesellschaft mit beschrankter Haftung, Aachen, Germany, a corporation of Germany Filed Oct. 26, 1967, Ser. No. 678,372 Claims priority, application Germany, Nov. 5, 1966, Sch 39,788 Int. Cl. F16f 15/22 US. Cl. 74573 Claims ABSTRACT OF THE DISCLOSURE Apparatus for statically balancing machines driving rotary components and having a hollow drive shaft containing an unbalanced weight includes an externally threaded elongated cylindrical body extending through the weight. Received in the thread is a projection fixed to the weight and having a profile matching that of the thread. The thread has a pitch large enough to effect rotary movement of the weight in response to axial movement of the cylindrical body. Also provided are means for axially shifting the cylindrical body to change the angular position of the weight relative to the drive shaft.

My invention relates to a machine, such as a grinding machine, which is required to be statically balanced.

Although structures for statically balancing machines of this type are known, the known structures are'relatively complex and difficult to have the components thereof assembled. Furthermore, it is ditficult to achieve a high degree of precision in the positioning of the balancing weights with the conventional constructions.

'It is accordingly a primary object of my invention to provide a construction of the above type which is exceedingly simple and made up of components which can be easily assembled, while at the same time assuring a high degree of precision in the adjustment so as to achieve a high degree of static balance.

It is also an object of my invention to provide a construction which while including, for example, a pair of unbalanced weights which are independently adjustable, nevertheless is exceedingly compact without sacrificing any of the above highly desirable features such as case of assembly, precision in adjustment, and simplicity in construction.

Also, it is an object of my invention to provide a construction made up of components which can be fully manufactured before they are assembled together.

Thus, in accordance with my invention, the elongated hollow drive shaft which is supported for rotation about its axis and which drives the rotary components of the machine has in its interior an elongated cylindrical body which extends coaxially along the drive shaft. An unbal anced weight surrounds the cylindrical body and is also located within the drive shaft, and the cylindrical body has at its exterior a spiral thread which receives a projection fixed to and projecting from the Weight and having a profile matching that of the thread. The spiral thread has a pitch great enough to provide for rotary movement of the weight in response to axial shifting of the cylindrical body. Situated in the region of and space axially along the cylindrical body are a pair of means one of which rotate with but is axially immovable with respect to the drive shaft and the other of which is axially movable with respect to but does not rotate with the holice low drive shaft. A connecting means connects this one of the pair of means to the cylindrical body in a manner providing for axial movement of the cylindrical body with respect to this one of the pair of means while preventing rotary movement of the cylindrical body with respect to this one of the pair of means, so that in this way the cylindrical body is constrained to rotate with the hollow drive shaft while being axially movable with respect thereto. A connecting means connects the other of the pair of means to the cylindrical body in a manner preventing axial movement thereof with respect to this other means but freeing the cylindrical body for rotary movement with respect to this other means, and an adjusting means coacts with this other means for axially shifting the latter with respect to the cylindrical body, so that in response to axial shifting of this other one of the pair of means by the adjusting means the cylindrical body will be axially shifted while rotating with the drive shaft, thus providing a relative angular displacement between the unbalanced weight and the drive shaft, to achieve static balance.

My invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 is a longitudinal sectional elevation illustrating in a partly schematic manner one possible embodiment of the structure of my invention;

FIG. 2 is a transverse section of structure shown at the region of the left of FIG. 1 taken along line IIII of FIG. 1 inthe direction of the arrows;

FIG. 3 is a transverse section of structure just to the right of FIG. 2 taken along line IIIIII of FIG. 1 in the direction of the arrows; and

FIG. 4 is a transverse section of structure shown in the region of the right of FIG. 1, taken along line IVIV of FIG. 1 in the direction of the arrows.

Referring to FIG. 1, there is schematically illustrated therein how an elongated hollow drive shaft 14, driven in any suitable well known manner which is not illustrated, is connected with a rotary component of the machine such as a grinding Wheel 21 which is driven upon rotation of the shaft 14.

Situated within the elongated hollow drive shaft 14, which is supported for rotation about its axis by the ball bearings 22 schematically shown in FIG. 1 carried by parts of the machine frame 23, are a pair of unbalanced weights 1 and 2 which are capable of being angularly adjusted with respect to the shaft 14 but which are incapable of shifting axially therein.

The unbalanced weight 1 is maintained in the illustrated axial position by a pair of thrust needle bearings 30: which are situated in the hollow shaft 14 in engagement with opposed side faces of the unbalanced Weight 1, respectively. In a similar manner the unbalanced weight 2 is maintained in the illustrated axial position by a pair of thrust needle bearings 3b which respectively engage opposed side faces of the unbalanced weight 2. These unbalanced weights together with the thrust needle bearings which engage their opposed faces are maintained in the illustrated axial positions by a series of sleeves 4, 5, 6. The left sleeve 4 of FIG. 1 is fixed to the left end of the shaft 14 and engages the left bearing 3a, while the right sleeve or exterior bearing 6 is also fixed to the shaft 14 and extends into the latter, this sleeve engaging the right bearing 3b. The intermediate sleeve or exterior bearing 5 extends between and engages the right bearing 3a and the left bearing 3b of of FIG. 1, so that with this assembly the unbalanced weights will be maintained in their illustrated axial positions only for rotary angular movement with respect to the shaft 14 while of course at the same time being capable of rotating therewith.

A pair of cylindrical bodies 11 and 19 are coaxially situated in the hollow shaft 14 and respectively surrounded by the unbalanced weights 1 and 2. These elongated cylindrical bodies 11 and 19 are respectively provided at their exteriors with threads of a pitch large enough to provide for turning of an element engaging these threads in response to axial movement of the cylindrical bodies. In the illustrated example these threads are in the form of grooves in the exterior surfaces of the cylindrical bodies 11 and 19. The unbalanced weights 1 and 2 are respectively provided with projections of profiles matching that of the threads of the cylindrical bodies 11 and 19 and received in these threads, so that in this way the unbalanced weights will be capable of angular adjustment in response to axial shifting movement of the cylindrical bodies 11 and 19 with respect to the shaft 14.

For this purpose each of the cylindrical bodies 11 and 19 is situated in the region of a pair of means one of which rotates with the shaft 14 and the other of which does not rotate with the shaft 14 and instead remains stationary during operation of the machine. Thus, in the illustrated example the left end of the cylindrical body 11 is situated in the region of the ring or sleeve 4 which is fixed to the shaft 14 for rotation therewith, while the right end of the cylindrical body 11 is situated in the region of the cup-shaped body 9 which remains stationary during operation of the machine. In the same way the left end of the cylindrical body 19 is surrounded by the sleeve which rotates together with the shaft 14 while the right end of the cylindrical body 19 is surrounded by the cupshaped body 20 which remains stationary during operation of the machine.

In addition, one connecting means connects each cylindrical body to that means which rotates with the shaft 14 for axial movement with respect to the latter means while preventing angular movement of the cylindrical body with respect to the latter means, and a second connecting means is provided for connecting each cylindrical body to that means which remains stationary during operation of the machine for free rotary movement with respect thereto while preventing axial movement of the cylindrical body with respect to the means which remains stationary during operation of the machine. For this purpose the left ends of the cylindrical bodies 11 and 19, as viewed in FIG. 1, are respectively fixed with a pair of discs 15a and 15b, by way of the off-center set screws 16a and 16b (FIG. 2), and these discs 15a and 15b are respectively slidably keyed to the members 4 and 5 by way of keys 13a and 13b, respectively. Thus, the left ends of the cylindrical bodies 11 and 19 are connected to the pair of means 4 and 5 which rotate with shaft 14 by structures which will provide for axial shifting of the cylindrical bodies but which will prevent rotary movement of the cylindrical bodies with respect to the shaft 14.

The connecting means for connecting the cylindrical bodies to the pair of means 9 and 20 which remain stationary take the form of a pair of thrust ball bearings a and 10b which are respectively surrounded and carried by the cup-shaped bodies 9 and 20 and which are operatively connected with the cylindrical bodies 11 and 19 in the region of their right ends, respectively, as viewed in FIG. 1, so that these hearings 10a and 10b, which are capable of absorbing axial thrust forces as well as supporting the cylindrical bodies for rotary movement, connect the cylindrical bodies to the pair of stationary means 9 and 20 for free rotary movement with respect thereto while preventing axial movement of the cylindrical bodies 11 and 19 with respect to the cup-shaped bodies 9 and 20 which remain stationary during operation of the machine.

An adjusting means is provided for adjusting the axial positions of the cup-shaped bodies 9 and 20 which remain stationary except when they are adjusted, and in this way the axial positions of the cylindrical bodies 11 and 19 will also be adjusted. The adjusting means in- .4 cludes an elongated spindle 8 which extends co-axially and slidably through the axially bored cylindrical body 19 and which is connected at its left end to the cupshaped body 9. The right end of the spindle 8, as viewed in FIG. 1, is threaded and carries a threaded knob 7 which is manually turned so as to adjust the axial position of the spindle 8 and thus the axial position of the cupshaped body 9 and the cylindrical body 11. As is apparent from FIG. 4 the side surfaces of the spindle 8 in the region of the knob 7 are flat, and the machine frame structure has a substantially rectangular opening through which this part of the spindle 8 extends so as to slidably engage the flat side surfaces, and thus the spindle 8 is incapable of rotating about its axis, so that the cup-shaped body 9 also will not rotate about its axis, and it will be noted that axially extending needle bearing members 24 surround the body 9 and engage the inner surface of the sleeve 5, so that in this way the body 9 is capable of shifting axially while being constrained against rotary movement. Furthermore, according to a preferred construction of the invention the rotary adjusting knob 7 is carried by the frame structure in such a way that it is free to turn but cannot move axially, so that by turning the knob 7 it is possible to adjust the position of the cylindrical body 11, and the pin 12 which is fixed to and projects radially from the unbalance weight 1 into the thread of the cylindrical body 11 will respond to axial movement of the latter to provide for angular adjustment of the unbalanced weight 1 with respect to the shaft 14 in response to turning of the knob 7. The unbalanced configuration of the weight 1 is apparent from FIG. 3, so that the result of angular positioning of the weight 1 with respect to the shaft 14 will provide for static balance.

In much the same way the cup-shaped body 20 is fixed to a threaded spindle 18 which is axially bored so as to provide for the passage of the spindle 8 therethrough, and the threaded spindle 18 is also constrained against rotary movement as by a pin 12 which extends into an axial groove formed in the exterior surface of the threaded spindle 8, as is indicated in FIG. 1. The stationary frame structure 23 carries a rotary knob 17 which is accessible to the operator and which is prevented from moving axially, and this knob 17 coacts with the threads formed at the exterior of the spindle 18, so that in response to turning of the knob 17 the spindle 18 will move axially and will provide for axial movement of the cup-shaped body 20 which is supported for rotary movement in the sleeve 6 by way of a needle bearing 25 in the same way as the cup-shaped body 9. Therefore, rotary movement of the knob 17 will result in axial displacement of the cylindrical body 19, and the pin 12 of the unbalanced weight 2 will therefore be angularly turned so as to turn the weight 2 and thus achieve static balance at the latter weight.

It is therefore apparent that with the structure of the invention the simple manual turning of the knobs 7 and 17 will result only in angular adjustment of the unbalstatic balance. Moreover, the structure is extremely comaced weights with respect to the shaft 14, so as to achieve pact as a result of the axial bores formed in the cylindrical body 19 and in the spindle 18 so as to permit the spindle 8 to pass through the spindle 18 and the cylindrical body 19, as Well as through the cup-shaped body 20, to be connected to the cup-shaped body 9. Moreover, all of the components, such as, for example, the unbalanced weights 1 and 2 and the cup-shaped bodies 9 and 20 can be fully manufactured before they are assembled, and the assembly of the components is very easy to carry out.

Thus, with the structure of my invention it is unnecessary to provide the unbalanced weights with any threads and it is unnecessary to axially shift the unbalanced weights 1 and 2. The elimination of the necessity for axial shifting of these unbalanced weights is in and of itself a great advantage in connection with the achieving of static balance.

The requirement only of connection of the large-pitch threads of the cylindrical bodies 11 and 19 to the unbalanced weights by way of the pins 12 which are respectively fixed to the latter is an exceedingly simple construction capable of achieving the desired results in a highly eflicient manner.

It will be noted also that the discs 15a and 15b are of an exceedingly simple construction and are very easy to assemble with the remaining components, so as to achieve the connection of the cylindrical bodies to the shaft 14 for rotary movement therewith and for axial movement with respect thereto. Furthermore, it will be seen that the discs 15a and 15b are guided for slidable shifting movement at their exterior peripheral surfaces which slidably engage the inner cylindrical surfaces of the sleeves 4 and 5 which are coaxially fixed in the interior of the shaft 14, so that with this exceedingly simple construction a highly efiicient guiding of the cylindrical bodies 11 and 19 is achieved. While it would of course be possible to use the inner surface of the shaft 14 itself to guide such elements as the discs 15a and 15b, it is preferred to use separate sleeves 4 and 5 which themselves are fixed to the shaft 14 so as to simplify and render the assembly easier to carry out.

The fact that the components 19, 20 and 18 are axially bored to permit the spindle 8 to extend through these components to be fixed to the cup-shaped body 9 not only provides for a compact assembly, but in addition it enables the unbalanced weights to be arranged one after the other axially along the interior of the shaft 14 and it in addition enables the adjusting knobs 7 and 17 to be situated on the same side of the machine closely adjacent to each other which provides the best possible arrangement from the standpoint of the operations which are carried out in connection with adjusting of the machine by the operator.

Of course, it is also possible to provide an arrangement where the adjusting spindles rotate and have the adjusting knobs fixed thereto for rotation therewith, with the spindles in this case extending through stationary nuts or the like, but this latter arrangement is far inferior to that shown with the structure of my invention in the drawings and described above. With an arrangement where the adjusting knobs are fixed to the rotary adjusting spindles the adjusting knobs will not remain at all times in the same plane but instead will necessarily shift axially with the spindles. This is of considerable disadvantage particularly in the case where the adjusting knobs are to coact with graduations of scales which will indicate the adjusted positions of the unbalanced weights. However, with a construction as described above and shown in the drawings, in accordance with my invention, the adjusting knobs remain at all times in the same plane and therefore can easily coact with suitable scales which can be rendered very readily visible in the best possible manner, so that this is a particular advantage of the structure of my invention.

As has been pointed out above, a considerable advantage is achieved with the structure of my invention by arranging the unbalanced weights so that they need not move axially but are only adjusted angularly with respect to the shaft 14. The great advantage which is achieved from this feature is that the common center of gravity of both the unbalanced weights does not change during the adjustments to achieve static balance, and therefore if there should be any dynamic unbalance present, this latter dynamic unbalance will not be influenced by the static balancing achieved with the structure of my invention.

Furthermore, it is to be noted that the thrust needle bearings 3a and 3b which engage and support the weights for angular adjustment are very easy to assemble with the remaining components and provide in a highly reliable manner an assurance against axial displacement of the weights 1 and 2. At the same time these needle bearings 3a and 3b permit angular adjustments to be carried out with very little frictional resistance so that the adjusting knobs 7 and 17 can be turned very easily to provide highly accurate adjustments.

I claim:

1. In an apparatus for statically balancing a machine which drives rotary components, an elongated hollow drive shaft supported for rotation about its axis and adapted to drive the rotary components of the machine, an elongated cylindrical body extending coaxially along the interior of said hollow drive shaft, an unbalanced weight situated within said hollow drive shaft surrounding said elongated cylindrical body, said body being formed at its exterior with an elongated spiral thread and said weight having an inner projection extending into said thread and of a profile matching the latter, said thread having a pitch great enough to provide for rotary movement between said weight and body, one relative to the other, in response to axial movement of said body with respect to said weight, a pair of means situated adjacent and respectively spaced axially from each other along said body, one of said pair of means being connected to said hollow drive shaft for rotary movement therewith and the other of said pair of means being axially movable with respect to said hollow drive shaft but otherwise remaining stationary while said drive shaft rotates with respect thereto, connecting means connecting said body to said one of said pair of means for rotation therewith and only for axial movement with respect thereto, connecting means connecting said body to said other of said pair of means for rotary movement with respect thereto while preventing axial movement of said body with respect to said other of said pair of means, and adjusting means coacting with said other of said pair of means for adting the latter axially with respect to said shaft, so as to adjust said cylindrical body axially with respect to said shaft while said cylindrical body rotates with said shaft and angularly adjusts said unbalanced weight with respect thereto.

2. The combination of claim 1 and wherein said thread is in the form of a groove in the exterior surface of said cylindrical body and said projection is in the form of a pin extending radially from said weight, fixed thereto, and received in said groove.

3. The combination of claim 2 and wherein said one of said pair of means which rotates with said drive shaft has an inner slide surface surrounding at least part of said cylindrical body, said connecting means for connecting the latter to said one of said pair of means including a disc to which said cylindrical body is centrally fixed, said disc having an outer peripheral surface slidably engaging said slide surface and axially keyed thereto for axial movement while being prevented from rotating with respect thereto.

4. The combination of claim 3 and wherein said one of said pair of means is in the form of a ring-shaped rotary member coaxially fixed to said shaft for rotation therewith and having said inner slide surface which is engaged by said outer peripheral surface of said disc.

5. The combination of claim 4 and wherein said other of said pair of means which is axially shiftable with respect to but does not rotate with said shaft is in the form of a cup-shaped body uniformly distributed about the axis of said drive shaft and fixed to said adjusting means, said connecting means for connecting said cup-shaped body to said cylindrical body including a 'ball bearing carried by said cup-shaped body in the interior thereof and co axially surrounding and operatively connected with said cylindrical body for absorbing axial forces as well as for serving as a bearing which supports said cylindrical body for rotary movement, and an exterior bearing surrounding said cup-shaped body and supporting said shaft for rotary movement with respect thereto while freeing said body for axial movement with respect to said shaft, said hearing which surrounds said cup-shaped body engaging an inner cylindrical surface in the interior of said hollow shaft which coaxially surrounds the axis thereof.

6. The combination of claim and wherein a pair of said unbalanced weights are situated Within said hollow drive shaft axially spaced therealong and respectively coacting with a pair of said cylindrical bodies with each of which said one and said other of said pair of means are operatively connected by the two connecting means which connect each of said cylindrical bodies to the pair of connecting means for axial but nonrotary movement and for rotary but nonaxial movement, and a pair of adjusting means for axially adjusting said cylindrical bodies, respectively, one of said cylindrical bodies and the cup-shaped body connected thereto being axially bored and one of said adjusting means including a threaded spindle which extends through said one cylindrical body and said one cup-shaped body to be operatively connected to the cup-shaped body which is connected with the other of said cylindrical bodies, and said one axially bored cup-shaped body having operatively connected thereto an adjusting means in the form of an axially bored threaded spindle through which the threaded spindle connected to the other of said cup-shaped bodies coaxially extends.

7. The combination of claim 6 and wherein a pair of rotary adjusting knobs are threadedly connected with said spindles for axially shifting the latter, means coacting with said pair of spindles for preventing rotary movement thereof while freeing the latter for axial movement, and means coacting with said knobs for preventing axial movement of the latter while freeing the latter for rotary movement, so that said knobs are free to turn without being axially displaced during axial adjustment of said spindles.

8. The combination of claim 1 and wherein a means coacts with said unbalanced weight for preventing axial movement therewith with respect to said drive shaft.

9. The combination of claim 8 and wherein said means which prevents axial movement of said weight includes a pair of needle bearings situated at opposite ends of said weight, guiding the latter for rotary movement about the axis of said shaft, and axially fixed to said shaft so as to be incapable of axial movement with respect thereto.

10. The combination of claim 7 and wherein a pair of means respectively coact with the pair of unbalanced weights for preventing axial movement thereof with respect to said shaft while freeing said weights for angular movement with respect to said shaft.

FOREIGN PATENTS 611,152 10/1960 Italy.

FRED C. MATTERN, JR., Primary Examiner F. D. SHOEMAKER, Assistant Examiner US. Cl. X.R. 

